// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause

//go:build !plan9

package spdy

import (
	"bytes"
	"compress/zlib"
	"io"
)

// zlibReader contains functionality to parse zlib compressed SPDY data.
// See https://www.ietf.org/archive/id/draft-mbelshe-httpbis-spdy-00.txt section 2.6.10.1
type zlibReader struct {
	io.ReadCloser
	underlying io.LimitedReader // zlib compressed SPDY data
}

// Read decompresses zlibReader's underlying zlib compressed SPDY data and reads
// it into b.
func (z *zlibReader) Read(b []byte) (int, error) {
	if z.ReadCloser == nil {
		r, err := zlib.NewReaderDict(&z.underlying, spdyTxtDictionary)
		if err != nil {
			return 0, err
		}
		z.ReadCloser = r
	}
	return z.ReadCloser.Read(b)
}

// Set sets zlibReader's underlying data. b must be zlib compressed SPDY data.
func (z *zlibReader) Set(b []byte) {
	z.underlying.R = bytes.NewReader(b)
	z.underlying.N = int64(len(b))
}

// spdyTxtDictionary is the dictionary defined in the SPDY spec.
// https://datatracker.ietf.org/doc/html/draft-mbelshe-httpbis-spdy-00#section-2.6.10.1
var spdyTxtDictionary = []byte{
	0x00, 0x00, 0x00, 0x07, 0x6f, 0x70, 0x74, 0x69, // - - - - o p t i
	0x6f, 0x6e, 0x73, 0x00, 0x00, 0x00, 0x04, 0x68, // o n s - - - - h
	0x65, 0x61, 0x64, 0x00, 0x00, 0x00, 0x04, 0x70, // e a d - - - - p
	0x6f, 0x73, 0x74, 0x00, 0x00, 0x00, 0x03, 0x70, // o s t - - - - p
	0x75, 0x74, 0x00, 0x00, 0x00, 0x06, 0x64, 0x65, // u t - - - - d e
	0x6c, 0x65, 0x74, 0x65, 0x00, 0x00, 0x00, 0x05, // l e t e - - - -
	0x74, 0x72, 0x61, 0x63, 0x65, 0x00, 0x00, 0x00, // t r a c e - - -
	0x06, 0x61, 0x63, 0x63, 0x65, 0x70, 0x74, 0x00, // - a c c e p t -
	0x00, 0x00, 0x0e, 0x61, 0x63, 0x63, 0x65, 0x70, // - - - a c c e p
	0x74, 0x2d, 0x63, 0x68, 0x61, 0x72, 0x73, 0x65, // t - c h a r s e
	0x74, 0x00, 0x00, 0x00, 0x0f, 0x61, 0x63, 0x63, // t - - - - a c c
	0x65, 0x70, 0x74, 0x2d, 0x65, 0x6e, 0x63, 0x6f, // e p t - e n c o
	0x64, 0x69, 0x6e, 0x67, 0x00, 0x00, 0x00, 0x0f, // d i n g - - - -
	0x61, 0x63, 0x63, 0x65, 0x70, 0x74, 0x2d, 0x6c, // a c c e p t - l
	0x61, 0x6e, 0x67, 0x75, 0x61, 0x67, 0x65, 0x00, // a n g u a g e -
	0x00, 0x00, 0x0d, 0x61, 0x63, 0x63, 0x65, 0x70, // - - - a c c e p
	0x74, 0x2d, 0x72, 0x61, 0x6e, 0x67, 0x65, 0x73, // t - r a n g e s
	0x00, 0x00, 0x00, 0x03, 0x61, 0x67, 0x65, 0x00, // - - - - a g e -
	0x00, 0x00, 0x05, 0x61, 0x6c, 0x6c, 0x6f, 0x77, // - - - a l l o w
	0x00, 0x00, 0x00, 0x0d, 0x61, 0x75, 0x74, 0x68, // - - - - a u t h
	0x6f, 0x72, 0x69, 0x7a, 0x61, 0x74, 0x69, 0x6f, // o r i z a t i o
	0x6e, 0x00, 0x00, 0x00, 0x0d, 0x63, 0x61, 0x63, // n - - - - c a c
	0x68, 0x65, 0x2d, 0x63, 0x6f, 0x6e, 0x74, 0x72, // h e - c o n t r
	0x6f, 0x6c, 0x00, 0x00, 0x00, 0x0a, 0x63, 0x6f, // o l - - - - c o
	0x6e, 0x6e, 0x65, 0x63, 0x74, 0x69, 0x6f, 0x6e, // n n e c t i o n
	0x00, 0x00, 0x00, 0x0c, 0x63, 0x6f, 0x6e, 0x74, // - - - - c o n t
	0x65, 0x6e, 0x74, 0x2d, 0x62, 0x61, 0x73, 0x65, // e n t - b a s e
	0x00, 0x00, 0x00, 0x10, 0x63, 0x6f, 0x6e, 0x74, // - - - - c o n t
	0x65, 0x6e, 0x74, 0x2d, 0x65, 0x6e, 0x63, 0x6f, // e n t - e n c o
	0x64, 0x69, 0x6e, 0x67, 0x00, 0x00, 0x00, 0x10, // d i n g - - - -
	0x63, 0x6f, 0x6e, 0x74, 0x65, 0x6e, 0x74, 0x2d, // c o n t e n t -
	0x6c, 0x61, 0x6e, 0x67, 0x75, 0x61, 0x67, 0x65, // l a n g u a g e
	0x00, 0x00, 0x00, 0x0e, 0x63, 0x6f, 0x6e, 0x74, // - - - - c o n t
	0x65, 0x6e, 0x74, 0x2d, 0x6c, 0x65, 0x6e, 0x67, // e n t - l e n g
	0x74, 0x68, 0x00, 0x00, 0x00, 0x10, 0x63, 0x6f, // t h - - - - c o
	0x6e, 0x74, 0x65, 0x6e, 0x74, 0x2d, 0x6c, 0x6f, // n t e n t - l o
	0x63, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x00, 0x00, // c a t i o n - -
	0x00, 0x0b, 0x63, 0x6f, 0x6e, 0x74, 0x65, 0x6e, // - - c o n t e n
	0x74, 0x2d, 0x6d, 0x64, 0x35, 0x00, 0x00, 0x00, // t - m d 5 - - -
	0x0d, 0x63, 0x6f, 0x6e, 0x74, 0x65, 0x6e, 0x74, // - c o n t e n t
	0x2d, 0x72, 0x61, 0x6e, 0x67, 0x65, 0x00, 0x00, // - r a n g e - -
	0x00, 0x0c, 0x63, 0x6f, 0x6e, 0x74, 0x65, 0x6e, // - - c o n t e n
	0x74, 0x2d, 0x74, 0x79, 0x70, 0x65, 0x00, 0x00, // t - t y p e - -
	0x00, 0x04, 0x64, 0x61, 0x74, 0x65, 0x00, 0x00, // - - d a t e - -
	0x00, 0x04, 0x65, 0x74, 0x61, 0x67, 0x00, 0x00, // - - e t a g - -
	0x00, 0x06, 0x65, 0x78, 0x70, 0x65, 0x63, 0x74, // - - e x p e c t
	0x00, 0x00, 0x00, 0x07, 0x65, 0x78, 0x70, 0x69, // - - - - e x p i
	0x72, 0x65, 0x73, 0x00, 0x00, 0x00, 0x04, 0x66, // r e s - - - - f
	0x72, 0x6f, 0x6d, 0x00, 0x00, 0x00, 0x04, 0x68, // r o m - - - - h
	0x6f, 0x73, 0x74, 0x00, 0x00, 0x00, 0x08, 0x69, // o s t - - - - i
	0x66, 0x2d, 0x6d, 0x61, 0x74, 0x63, 0x68, 0x00, // f - m a t c h -
	0x00, 0x00, 0x11, 0x69, 0x66, 0x2d, 0x6d, 0x6f, // - - - i f - m o
	0x64, 0x69, 0x66, 0x69, 0x65, 0x64, 0x2d, 0x73, // d i f i e d - s
	0x69, 0x6e, 0x63, 0x65, 0x00, 0x00, 0x00, 0x0d, // i n c e - - - -
	0x69, 0x66, 0x2d, 0x6e, 0x6f, 0x6e, 0x65, 0x2d, // i f - n o n e -
	0x6d, 0x61, 0x74, 0x63, 0x68, 0x00, 0x00, 0x00, // m a t c h - - -
	0x08, 0x69, 0x66, 0x2d, 0x72, 0x61, 0x6e, 0x67, // - i f - r a n g
	0x65, 0x00, 0x00, 0x00, 0x13, 0x69, 0x66, 0x2d, // e - - - - i f -
	0x75, 0x6e, 0x6d, 0x6f, 0x64, 0x69, 0x66, 0x69, // u n m o d i f i
	0x65, 0x64, 0x2d, 0x73, 0x69, 0x6e, 0x63, 0x65, // e d - s i n c e
	0x00, 0x00, 0x00, 0x0d, 0x6c, 0x61, 0x73, 0x74, // - - - - l a s t
	0x2d, 0x6d, 0x6f, 0x64, 0x69, 0x66, 0x69, 0x65, // - m o d i f i e
	0x64, 0x00, 0x00, 0x00, 0x08, 0x6c, 0x6f, 0x63, // d - - - - l o c
	0x61, 0x74, 0x69, 0x6f, 0x6e, 0x00, 0x00, 0x00, // a t i o n - - -
	0x0c, 0x6d, 0x61, 0x78, 0x2d, 0x66, 0x6f, 0x72, // - m a x - f o r
	0x77, 0x61, 0x72, 0x64, 0x73, 0x00, 0x00, 0x00, // w a r d s - - -
	0x06, 0x70, 0x72, 0x61, 0x67, 0x6d, 0x61, 0x00, // - p r a g m a -
	0x00, 0x00, 0x12, 0x70, 0x72, 0x6f, 0x78, 0x79, // - - - p r o x y
	0x2d, 0x61, 0x75, 0x74, 0x68, 0x65, 0x6e, 0x74, // - a u t h e n t
	0x69, 0x63, 0x61, 0x74, 0x65, 0x00, 0x00, 0x00, // i c a t e - - -
	0x13, 0x70, 0x72, 0x6f, 0x78, 0x79, 0x2d, 0x61, // - p r o x y - a
	0x75, 0x74, 0x68, 0x6f, 0x72, 0x69, 0x7a, 0x61, // u t h o r i z a
	0x74, 0x69, 0x6f, 0x6e, 0x00, 0x00, 0x00, 0x05, // t i o n - - - -
	0x72, 0x61, 0x6e, 0x67, 0x65, 0x00, 0x00, 0x00, // r a n g e - - -
	0x07, 0x72, 0x65, 0x66, 0x65, 0x72, 0x65, 0x72, // - r e f e r e r
	0x00, 0x00, 0x00, 0x0b, 0x72, 0x65, 0x74, 0x72, // - - - - r e t r
	0x79, 0x2d, 0x61, 0x66, 0x74, 0x65, 0x72, 0x00, // y - a f t e r -
	0x00, 0x00, 0x06, 0x73, 0x65, 0x72, 0x76, 0x65, // - - - s e r v e
	0x72, 0x00, 0x00, 0x00, 0x02, 0x74, 0x65, 0x00, // r - - - - t e -
	0x00, 0x00, 0x07, 0x74, 0x72, 0x61, 0x69, 0x6c, // - - - t r a i l
	0x65, 0x72, 0x00, 0x00, 0x00, 0x11, 0x74, 0x72, // e r - - - - t r
	0x61, 0x6e, 0x73, 0x66, 0x65, 0x72, 0x2d, 0x65, // a n s f e r - e
	0x6e, 0x63, 0x6f, 0x64, 0x69, 0x6e, 0x67, 0x00, // n c o d i n g -
	0x00, 0x00, 0x07, 0x75, 0x70, 0x67, 0x72, 0x61, // - - - u p g r a
	0x64, 0x65, 0x00, 0x00, 0x00, 0x0a, 0x75, 0x73, // d e - - - - u s
	0x65, 0x72, 0x2d, 0x61, 0x67, 0x65, 0x6e, 0x74, // e r - a g e n t
	0x00, 0x00, 0x00, 0x04, 0x76, 0x61, 0x72, 0x79, // - - - - v a r y
	0x00, 0x00, 0x00, 0x03, 0x76, 0x69, 0x61, 0x00, // - - - - v i a -
	0x00, 0x00, 0x07, 0x77, 0x61, 0x72, 0x6e, 0x69, // - - - w a r n i
	0x6e, 0x67, 0x00, 0x00, 0x00, 0x10, 0x77, 0x77, // n g - - - - w w
	0x77, 0x2d, 0x61, 0x75, 0x74, 0x68, 0x65, 0x6e, // w - a u t h e n
	0x74, 0x69, 0x63, 0x61, 0x74, 0x65, 0x00, 0x00, // t i c a t e - -
	0x00, 0x06, 0x6d, 0x65, 0x74, 0x68, 0x6f, 0x64, // - - m e t h o d
	0x00, 0x00, 0x00, 0x03, 0x67, 0x65, 0x74, 0x00, // - - - - g e t -
	0x00, 0x00, 0x06, 0x73, 0x74, 0x61, 0x74, 0x75, // - - - s t a t u
	0x73, 0x00, 0x00, 0x00, 0x06, 0x32, 0x30, 0x30, // s - - - - 2 0 0
	0x20, 0x4f, 0x4b, 0x00, 0x00, 0x00, 0x07, 0x76, // - O K - - - - v
	0x65, 0x72, 0x73, 0x69, 0x6f, 0x6e, 0x00, 0x00, // e r s i o n - -
	0x00, 0x08, 0x48, 0x54, 0x54, 0x50, 0x2f, 0x31, // - - H T T P - 1
	0x2e, 0x31, 0x00, 0x00, 0x00, 0x03, 0x75, 0x72, // - 1 - - - - u r
	0x6c, 0x00, 0x00, 0x00, 0x06, 0x70, 0x75, 0x62, // l - - - - p u b
	0x6c, 0x69, 0x63, 0x00, 0x00, 0x00, 0x0a, 0x73, // l i c - - - - s
	0x65, 0x74, 0x2d, 0x63, 0x6f, 0x6f, 0x6b, 0x69, // e t - c o o k i
	0x65, 0x00, 0x00, 0x00, 0x0a, 0x6b, 0x65, 0x65, // e - - - - k e e
	0x70, 0x2d, 0x61, 0x6c, 0x69, 0x76, 0x65, 0x00, // p - a l i v e -
	0x00, 0x00, 0x06, 0x6f, 0x72, 0x69, 0x67, 0x69, // - - - o r i g i
	0x6e, 0x31, 0x30, 0x30, 0x31, 0x30, 0x31, 0x32, // n 1 0 0 1 0 1 2
	0x30, 0x31, 0x32, 0x30, 0x32, 0x32, 0x30, 0x35, // 0 1 2 0 2 2 0 5
	0x32, 0x30, 0x36, 0x33, 0x30, 0x30, 0x33, 0x30, // 2 0 6 3 0 0 3 0
	0x32, 0x33, 0x30, 0x33, 0x33, 0x30, 0x34, 0x33, // 2 3 0 3 3 0 4 3
	0x30, 0x35, 0x33, 0x30, 0x36, 0x33, 0x30, 0x37, // 0 5 3 0 6 3 0 7
	0x34, 0x30, 0x32, 0x34, 0x30, 0x35, 0x34, 0x30, // 4 0 2 4 0 5 4 0
	0x36, 0x34, 0x30, 0x37, 0x34, 0x30, 0x38, 0x34, // 6 4 0 7 4 0 8 4
	0x30, 0x39, 0x34, 0x31, 0x30, 0x34, 0x31, 0x31, // 0 9 4 1 0 4 1 1
	0x34, 0x31, 0x32, 0x34, 0x31, 0x33, 0x34, 0x31, // 4 1 2 4 1 3 4 1
	0x34, 0x34, 0x31, 0x35, 0x34, 0x31, 0x36, 0x34, // 4 4 1 5 4 1 6 4
	0x31, 0x37, 0x35, 0x30, 0x32, 0x35, 0x30, 0x34, // 1 7 5 0 2 5 0 4
	0x35, 0x30, 0x35, 0x32, 0x30, 0x33, 0x20, 0x4e, // 5 0 5 2 0 3 - N
	0x6f, 0x6e, 0x2d, 0x41, 0x75, 0x74, 0x68, 0x6f, // o n - A u t h o
	0x72, 0x69, 0x74, 0x61, 0x74, 0x69, 0x76, 0x65, // r i t a t i v e
	0x20, 0x49, 0x6e, 0x66, 0x6f, 0x72, 0x6d, 0x61, // - I n f o r m a
	0x74, 0x69, 0x6f, 0x6e, 0x32, 0x30, 0x34, 0x20, // t i o n 2 0 4 -
	0x4e, 0x6f, 0x20, 0x43, 0x6f, 0x6e, 0x74, 0x65, // N o - C o n t e
	0x6e, 0x74, 0x33, 0x30, 0x31, 0x20, 0x4d, 0x6f, // n t 3 0 1 - M o
	0x76, 0x65, 0x64, 0x20, 0x50, 0x65, 0x72, 0x6d, // v e d - P e r m
	0x61, 0x6e, 0x65, 0x6e, 0x74, 0x6c, 0x79, 0x34, // a n e n t l y 4
	0x30, 0x30, 0x20, 0x42, 0x61, 0x64, 0x20, 0x52, // 0 0 - B a d - R
	0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x34, 0x30, // e q u e s t 4 0
	0x31, 0x20, 0x55, 0x6e, 0x61, 0x75, 0x74, 0x68, // 1 - U n a u t h
	0x6f, 0x72, 0x69, 0x7a, 0x65, 0x64, 0x34, 0x30, // o r i z e d 4 0
	0x33, 0x20, 0x46, 0x6f, 0x72, 0x62, 0x69, 0x64, // 3 - F o r b i d
	0x64, 0x65, 0x6e, 0x34, 0x30, 0x34, 0x20, 0x4e, // d e n 4 0 4 - N
	0x6f, 0x74, 0x20, 0x46, 0x6f, 0x75, 0x6e, 0x64, // o t - F o u n d
	0x35, 0x30, 0x30, 0x20, 0x49, 0x6e, 0x74, 0x65, // 5 0 0 - I n t e
	0x72, 0x6e, 0x61, 0x6c, 0x20, 0x53, 0x65, 0x72, // r n a l - S e r
	0x76, 0x65, 0x72, 0x20, 0x45, 0x72, 0x72, 0x6f, // v e r - E r r o
	0x72, 0x35, 0x30, 0x31, 0x20, 0x4e, 0x6f, 0x74, // r 5 0 1 - N o t
	0x20, 0x49, 0x6d, 0x70, 0x6c, 0x65, 0x6d, 0x65, // - I m p l e m e
	0x6e, 0x74, 0x65, 0x64, 0x35, 0x30, 0x33, 0x20, // n t e d 5 0 3 -
	0x53, 0x65, 0x72, 0x76, 0x69, 0x63, 0x65, 0x20, // S e r v i c e -
	0x55, 0x6e, 0x61, 0x76, 0x61, 0x69, 0x6c, 0x61, // U n a v a i l a
	0x62, 0x6c, 0x65, 0x4a, 0x61, 0x6e, 0x20, 0x46, // b l e J a n - F
	0x65, 0x62, 0x20, 0x4d, 0x61, 0x72, 0x20, 0x41, // e b - M a r - A
	0x70, 0x72, 0x20, 0x4d, 0x61, 0x79, 0x20, 0x4a, // p r - M a y - J
	0x75, 0x6e, 0x20, 0x4a, 0x75, 0x6c, 0x20, 0x41, // u n - J u l - A
	0x75, 0x67, 0x20, 0x53, 0x65, 0x70, 0x74, 0x20, // u g - S e p t -
	0x4f, 0x63, 0x74, 0x20, 0x4e, 0x6f, 0x76, 0x20, // O c t - N o v -
	0x44, 0x65, 0x63, 0x20, 0x30, 0x30, 0x3a, 0x30, // D e c - 0 0 - 0
	0x30, 0x3a, 0x30, 0x30, 0x20, 0x4d, 0x6f, 0x6e, // 0 - 0 0 - M o n
	0x2c, 0x20, 0x54, 0x75, 0x65, 0x2c, 0x20, 0x57, // - - T u e - - W
	0x65, 0x64, 0x2c, 0x20, 0x54, 0x68, 0x75, 0x2c, // e d - - T h u -
	0x20, 0x46, 0x72, 0x69, 0x2c, 0x20, 0x53, 0x61, // - F r i - - S a
	0x74, 0x2c, 0x20, 0x53, 0x75, 0x6e, 0x2c, 0x20, // t - - S u n - -
	0x47, 0x4d, 0x54, 0x63, 0x68, 0x75, 0x6e, 0x6b, // G M T c h u n k
	0x65, 0x64, 0x2c, 0x74, 0x65, 0x78, 0x74, 0x2f, // e d - t e x t -
	0x68, 0x74, 0x6d, 0x6c, 0x2c, 0x69, 0x6d, 0x61, // h t m l - i m a
	0x67, 0x65, 0x2f, 0x70, 0x6e, 0x67, 0x2c, 0x69, // g e - p n g - i
	0x6d, 0x61, 0x67, 0x65, 0x2f, 0x6a, 0x70, 0x67, // m a g e - j p g
	0x2c, 0x69, 0x6d, 0x61, 0x67, 0x65, 0x2f, 0x67, // - i m a g e - g
	0x69, 0x66, 0x2c, 0x61, 0x70, 0x70, 0x6c, 0x69, // i f - a p p l i
	0x63, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x2f, 0x78, // c a t i o n - x
	0x6d, 0x6c, 0x2c, 0x61, 0x70, 0x70, 0x6c, 0x69, // m l - a p p l i
	0x63, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x2f, 0x78, // c a t i o n - x
	0x68, 0x74, 0x6d, 0x6c, 0x2b, 0x78, 0x6d, 0x6c, // h t m l - x m l
	0x2c, 0x74, 0x65, 0x78, 0x74, 0x2f, 0x70, 0x6c, // - t e x t - p l
	0x61, 0x69, 0x6e, 0x2c, 0x74, 0x65, 0x78, 0x74, // a i n - t e x t
	0x2f, 0x6a, 0x61, 0x76, 0x61, 0x73, 0x63, 0x72, // - j a v a s c r
	0x69, 0x70, 0x74, 0x2c, 0x70, 0x75, 0x62, 0x6c, // i p t - p u b l
	0x69, 0x63, 0x70, 0x72, 0x69, 0x76, 0x61, 0x74, // i c p r i v a t
	0x65, 0x6d, 0x61, 0x78, 0x2d, 0x61, 0x67, 0x65, // e m a x - a g e
	0x3d, 0x67, 0x7a, 0x69, 0x70, 0x2c, 0x64, 0x65, // - g z i p - d e
	0x66, 0x6c, 0x61, 0x74, 0x65, 0x2c, 0x73, 0x64, // f l a t e - s d
	0x63, 0x68, 0x63, 0x68, 0x61, 0x72, 0x73, 0x65, // c h c h a r s e
	0x74, 0x3d, 0x75, 0x74, 0x66, 0x2d, 0x38, 0x63, // t - u t f - 8 c
	0x68, 0x61, 0x72, 0x73, 0x65, 0x74, 0x3d, 0x69, // h a r s e t - i
	0x73, 0x6f, 0x2d, 0x38, 0x38, 0x35, 0x39, 0x2d, // s o - 8 8 5 9 -
	0x31, 0x2c, 0x75, 0x74, 0x66, 0x2d, 0x2c, 0x2a, // 1 - u t f - - -
	0x2c, 0x65, 0x6e, 0x71, 0x3d, 0x30, 0x2e, // - e n q - 0 -
}
